Hello,
I believe the 2 questions you asked are esentially the same question.
Generally speaking, there are 2 control mode in motor control applications: speed or torque.
In speed control mode, you'll have to design a speed control loop and torque is given as load to the shaft of the motor. In this mode you cannot specifiy the exact amount of torque generated by the motor - it is all up to the load torque and the governing mechanical equation.
In torque control mode, you design a torque loop ( most likely an open loop) and from which accurate torque control is possible. Speed of the motor will again have to be determined by load, but this time on a test bench we use the coupling motor as a constant speed source. Of course you can leave the motor uncoupled and freely accelerate, but that free acceleration would be out of control if you output a high torque.
